分类目录归档：earth
How old is the Earth?
Well, by counting the number of isotopes
in a sample of rock
that's undergone radioactive decay,
geologists have estimated the Earth's birthday,
when it first formed from a solar
We've all seen movies
about terrible insects from outer space
or stories of abduction by little green men,
but the study of life in the universe,
including the possibility of extraterrestrial life,
is
I've always collected baseball cards.
I first started playing baseball when I was eight years old,
and when my hometown, Red Sox won the World Series in 2004,
I began meeting many of the players
at au
Cloudy climate change: How clouds affect Earth's temperature.
Earth's average surface temperature has warmed by .8 Celsius since 1750.
When carbon dioxide concentrations in the atmosphere have doubled
Humans have observed comets for thousands of years
as their orbits have brought them within visible distance of Earth.
Appearing throughout historical records,
these mysterious lights that came out
There's an organism that changed the world.
It caused both the first mass extinction in Earth's history
and also paved the way for complex life.
How?
By sending the first free oxygen molecules into o
Without water, a human can only survive for about 100 hours.
But there's a creature so resilient that it can go without it for decades.
This one millimeter animal can survive both the hottest
and cold
From asteroids capable of destroying entire species,
to gamma-ray bursts and supernovae that could exterminate life on Earth,
outer space has no shortage of forces that could wreak havoc on our tiny
More than six thousand light years
from the surface of the earth,
a rapidly spinning neutron star
called the Black Widow pulsar
blasts its companion brown dwarf star with radiation
as the two orbit e
In 132 CE,
Chinese polymath Zhang Heng
presented the Han court with his latest invention.
This large vase, he claimed,
could tell them whenever an earthquake occurred in their kingdom–
including the